Friction welder and friction welding methods

ABSTRACT

This friction welder has a rotatable head that drives an annular friction welding tool of a temperature stable material across adjacent faces of workpieces held in a fixture. The tool is axially loaded against the workpieces and the resulting heat of friction in an annular weld zone generally corresponding to the dimensions of the tool causes material in the zone to plasticize and form a bond wiped across the adjacent faces which solidifies to connect the workpieces as the rotating friction engagement of the tool with the workpieces is terminated.

United States Patent Herman FRICTION WELDER AND FRICTION WELDING METHODS[75] Inventor: Stanley W. Herman, Nashville, Ind.

[73] Assignee: General Motors Corporation,

Detroit, Mich.

[22] Filed: Nov. 30, 1971 [21] Appl. No.: 203,263

[52] US. Cl. 29/470.3, 156/73 [51] Int. Cl. 323k 27/00, B29c 27/08 [58]Field of Search 156/73, 580; 228/2; 29/4703 [56] References Cited UNITEDSTATES PATENTS 2,779,998 2/l957 Bailey 29/4703 l,73l,390 l0/l929Mitchell 228/2 3,376,179 4/1968 Balmuth 29/470.3

[ Dec. 25, 1973 Klopstock et a] 29/4703 Hewitt 29/4703 PrimaryExaminer-Douglas .l. Drummond Attorney-W. E. Finken et al.

[ 57] ABSTRACT This friction welder has a rotatable head that drives anannular friction welding tool of a temperature stable material acrossadjacent faces of workpieces held in a fixture. The tool is axiallyloaded against the workpieces and the resulting heat of friction in anannular weld zone generally corresponding to the dimensions of the toolcauses material in the zone to plasticize and form a bond wiped acrossthe adjacent faces which solidifies to connect the workpieces as therotating friction engagement of the tool with the workpieces isterminated.

3 Claims, 4 Drawing Figures FRICTION WELDER AND FRICTION WELDING METHODSThis invention relates to welding and more particularly to frictionwelders and to friction welding methods.

Friction welding machines and methods have been successfully employedfor many years to bond and rigidly secure workpieces together. In thepast few years the employment of friction welding has rapidly increasedand with this advancement new and different machines and techniques areneeded.

In one class of friction welding, two relatively rotating workpieces arebrought together at an interface under load and the weld zoneplasticizes to form a bond for the workpieces. As the relative rotationstops by employing braking means or by natural runout, the bondsolidifies to rigidly secure the workpieces together. In another generalclassification of friction welding special movable tooling is employedwhich contacts and frictionally heats two workpieces until a bond isformed which solidifies on removal of the tooling to secure theworkpieces together.

While these prior art friction welders and methods are generallysatisfactory for their intended purposes they have been limited tospecial applications and generally have not been able to satisfactorilybond many arrangements of work. For example, the prior art frictionwelders have generally been unable to satisfactorily bond two workpiecestogether which have exposed faces located adjacent to one another. Thepresent invention provides a new machine and technique which canfrictionally weld many types of workpieces. With this invention theworkpieces can be located in a side by side relationship and theseworkpieces can be readily welded together across an exposed andgenerally coplanar surface. In a preferred embodiment of this invention,a plurality of metallic workpieces can be simultaneously welded in asingle operation without difficulty. This friction welder has arotatable head in which there is secured special tooling that comprisesa metallic welding bead or annulus of a material which is not adverselyaffected by the high temperatures produced during the friction weldprocess. This welding bead is brought under pressure into engagementwith exposed faces of the metallic workpieces arranged side by side. Inthe illustrated embodiment of the invention, the workpieces comprise aplurality of planet gear spindles which have been inserted in a circularpattern through the side faces of the carrier of a planetary gear set.As the rotating welding bead is brought into contact with the side plateof the carrier assembly properly indexed with the circle defined by thespindles local heat buildup is generated to cause a wiping type frictionweld to occur between the carrier and the spindles.

This invention thus provides a new and improved apparatus and method forjoining workpieces disposed in a close, side by side relationship. Inthe preferred embodiments of the invention all spindles can be hard withno draw for manual or machine staking. Also, all spindles can be lockedat the same time by a fast acting machine function to provide a materialadvantage in producing planetary type gear sets. In this invention thereis an improved workpiece holder for holding a planetary gear setstationary during welding but which can be longitudinally moved betweena loading-unloading position and a welding position.

These and other objects, features and advantages of this invention willbecome more apparent from the following detailed description anddrawings in which:

FIG. 1 is a side sectional view taken generally along lines ll of FIG. 2and shows a portion ofa friction welder and workpieces mounted in thewelder.

FIG. 2 is a front view, partly in section, taken generally along lines2-2 of FIG. 1 showing the workpiece after friction welding.

FIG. 3 is a view taken along lines 33 of FIG. 2, and

FIG. 4 is an enlarged view of a portion of FIG. 1.

In FIG. 1 there is a friction welder 10 having a headstock withrotatable drive spindle 12 driven by a suitable motor as disclosed inU.S. application Ser. No. 778,720, filed Nov. 25, 1968 by E. S. Ditto etal, now U.S. Pat. No. 3,627,189. The drive spindle has a head member 14mounted on a shoulder 15 of the spindle and is secured thereto by screws16. The head member has an annular recess 20 that receives a cylindricaladapter 22 which is secured to the head member by screws 24. There is anannular welding tool 26 ofa suitable temperature stable material, suchas aluminum oxide, which is mounted in an annular recess 27 in adapter22 and is secured therein by screws 28. This friction welding tool hasan annular outwardly projecting bead 32 which is adapted to contact thework to be welded to accomplish a wiping type friction weld as will beexplained below.

The welder 10 has a tailstock 34 which is fixed against rotation but canbe moved back and forth on a longitudinal axis for loading, welding andunloading operations by suitable motor mechanisms such as disclosed inthe above-identified patent application. The tailstock 34 has a fixtureassembly 36 secured thereto by screws 38. This assembly has a workpiecesupport 40 which has a projecting annular shoulder 42 formed withinternal teeth which mesh with teeth on the work which is here shown asa carrier 44 for the planet gears of a planetary gear set. The fixtureassembly further comprises an elongated tubular support 46 that has abase 48 fitted into a recess in support 40 and is secured thereto byscrews 50.

Disposed within the tubular support and adjacent to the free endthereofis a detent 56 which is normally biased into a projectingposition into contact with the end of sleeve portion 58 of the carrier44 to hold the carrier in loaded position on the tailstock.

As shown best in FIGS. 1 and 2 the carrier assembly is a one-piecemetallic casting having sides 60, 62 connected by intermediate portions64 that form pockets for a plurality of planet gears 66. Each of thesegears is rotatably mounted on a separate metallic spindle 68 whichextends between the sides and 62. When in position in the carrier theflat end of each spindle preferably is coplanar with the exposed surfaceof the side 62. However, good welds can be accomplished if thesesurfaces are not coplanar.

For starting an operating cycle the tailstock is moved to a retractedposition away from the headstock so that the carrier assembly 44 can beloaded onto the tubular support 46. When loaded, the teeth of the sideplate 60 mesh with those of the workpiece support 40 and the detent 56projects out of support 46 into engagement with the end of sleeveportion 58 of the carrier assembly to secure it in the loading position.The drive spindle 12 is rotatably driven by a flywheel such as disclosedin the above-identified application Ser. No.

778,720. The tailstock is then advanced longitudinally so that therotating annular bead 32 frictionally engages the side plate 62 alongthe base circle C established by the spindles 68. The rotating tool 27and the side plate are engaged under a load sufficient to cause thelocal heat buildup generally along this base circle. As the material ofthe base circle plasticizes, it is displaced forming annular beads 72and 74 on either side of annular groove 76. The plasticized materialmixes preferably in two weld areas 78 and 80 between each spindle 68 andthe side plate 62 to thereby form two wiping type friction welds betweeneach spindle and the side plate as the energy of rotation of the headmember and parts rotating therewith is converted to frictional heat bythe braking action at contact with the work. Thus the relative rotationis stopped by the braking effect as the rotational energy of the head isexpended in the form of weldment heat. Preferably after the rotation hasstopped the tailstock is moved to the retracted position for unloadingso that the rotation of the tool can be restored for another operatingcycle. In the retracted position the carrier assembly with the spindleswelded into position can be easily removed and replaced by a newassembly to be welded.

If desired sufficient energy can be discharged from the flywheel toeffect the welding and then the tailstock can be moved to the retractedposition while the flywheel is still rotating. With this procedure theflywheel can be rapidly brought back to a welding speed with a minimumexpenditure of energy. In both cases it will be appreciated that thebead 32 leaves substantially no deposit metal in the weld and the tool26 can be utilized for many weld cycles before replacement.

This friction welder and process can be readily employed to weld otherarrangement of workpieces. For example, plates of metal suitable forfriction welding can be arranged in a close side by side relationshippreferably contacting at a linear interface. The rotating welding toolof this invention can be advanced linearly, frictionally contacting theexposed surfaces of the plates above the interface, to plasticize andbond these workpieces together. In addition to metallic workpiecesselected plastics can be welded with this welder and method.

While a preferred friction welder and friction welding method has beenshown and described, other similar machines and methods will now beapparent to those skilled in the art. Therefore the scope andlimitations of this invention are set forth in the following claims.

I claim:

1. A method of friction welding workpieces together comprising the stepsof arranging first and second workpieces so that the workpieces haveside surfaces disposed in closely abutting relationship with each other,providing said workpieces with substantially coplanar upper surfaces,rotating and advancing a temperature-stable friction welding tool intofrictional engagement with said upper surfaces so that said tooltransversely intersects a line on said upper surfaces defined by theabutting side surfaces of said workpieces, continuing the rotation ofsaid toolso that said tool frictionally heats and plasticizes thematerial of said workpieces frictionally engaged by said tool, forming asingle groove in said plasticized material of said work piecestransverse of said line, wiping a portion of said plasticized materialof said first workpiece into the plasticized material of said secondworkpiece and simultaneously wiping a portion of said plasticizedmaterial of said first workpiece into the plasticized material of saidsecond workpiece, withdrawing said rotating tool from frictionalengagement with said workpieces, and allowing said plasticized materialto solidify to thereby rigidly join said first and second workpiecestogether.

2. A method of frictionally welding metallic workpieces togethercomprising the steps of forming a circular arrangement of spacedopenings in a supporting workpiece, inserting and maintaining additionalworkpieces in each of said openings, aligning the end faces of saidadditional workpieces with the face of said supporting workpiece,rotatably driving an annular friction welding bead of temperature-stablematerial relative to said workpiece at a speed sufficient tofrictionally weld the plurality of workpieces to said supportingworkpiece, linearly advancing said rotating welding bead toward saidworkpieces so that said bead simultaneously engages all of the faces ofsaid workpieces at a single predetermined position, maintaining saidrotating bead in contact with said workpieces at said predeterminedposition, forming an annular groove in said supporting workpiece thattransverses said faces ofsaid additional workpieces while frictionallyheating and plasticizing material of all of said workpieces in a weldzone generally defined by said groove by the continued rotation of saidbead, linearly withdrawing said bead from friction engagement with saidworkpieces and allowing said plasticized material to solidify andthereby weld said workpieces together.

3. A method of frictionally welding metallic workpieces togethercomprising the steps of providing a plurality of spaced openings in acurved path in a supporting workpiece, fitting an additional workpieceinto each of said openings, aligning the front face of said supportingworkpieces with the front faces of said additional workpieces so thatsaid faces are all substantially coplanar, providing an annular bead oftemperature stable material on a rotatable friction welding tool,rotatably driving said tool and said annular bead at a speed sufficientto frictionally weld said plurality of workpieces to said supportingworkpiece, linearly advancing said friction welder tool toward saidworkpiece, engaging said annular bead with said workpieces, continuerotating said bead so that said bead makes simultaneous annular contactwith said supporting workpieces and the front faces of said plurality ofsaid workpieces, forming an annular groove in said workpieces by holdingsaid rotating annular bead in fixed alignment with said workpieces,frictionally heating and plasticizing material of said workpieces in aweld zone defined by said groove, displacing and mix ing a portion ofsaid plasticized material of said supporting workpiece into theplasticized material of said additional workpieces and displacing andmixing a portion of said plasticized material of said additionalworkpieces into the plasticized material of said supporting workpiece,and allowing said plasticized material to solidify and cool to therebysimultaneously weld said workpieces together.

1. A method of friction welding workpieces together comprising the stepsof arranging first and second workpieces so that the workpieces haveside surfaces disposed in closely abutting relationship with each other,providing said workpieces with substantially coplanar upper surfaces,rotating and advancing a temperature-stable friction welding tool intofrictional engagement with said upper surfaces so that said tooltransversely intersects a line on said upper surfaces defined by theabutting side surfaces of said workpieces, continuing the rotation ofsaid tool so that said tool frictionally heats and plasticizes thematerial of said workpieces frictionally engaged by said tool, forming asingle groove in said plasticized material of said workpieces transverseof said line, wiping a portion of said plasticized material of saidfirst workpiece into the plasticized material of said second workpieceand simultaneously wiping a portion of said plasticized material of saidfirst workpiece into the plasticized material of said second workpiece,withdrawing said rotating tool from frictional engagement with saidworkpieces, and allowing said plasticized material to solidify tothereby rigidly join said first and second workpieces together.
 2. Amethod of frictionally welding metallic workpieces together comprisingthe steps of forming a circUlar arrangement of spaced openings in asupporting workpiece, inserting and maintaining additional workpieces ineach of said openings, aligning the end faces of said additionalworkpieces with the face of said supporting workpiece, rotatably drivingan annular friction welding bead of temperature-stable material relativeto said workpiece at a speed sufficient to frictionally weld theplurality of workpieces to said supporting workpiece, linearly advancingsaid rotating welding bead toward said workpieces so that said beadsimultaneously engages all of the faces of said workpieces at a singlepredetermined position, maintaining said rotating bead in contact withsaid workpieces at said predetermined position, forming an annulargroove in said supporting workpiece that transverses said faces of saidadditional workpieces while frictionally heating and plasticizingmaterial of all of said workpieces in a weld zone generally defined bysaid groove by the continued rotation of said bead, linearly withdrawingsaid bead from friction engagement with said workpieces and allowingsaid plasticized material to solidify and thereby weld said workpiecestogether.
 3. A method of frictionally welding metallic workpiecestogether comprising the steps of providing a plurality of spacedopenings in a curved path in a supporting workpiece, fitting anadditional workpiece into each of said openings, aligning the front faceof said supporting workpieces with the front faces of said additionalworkpieces so that said faces are all substantially coplanar, providingan annular bead of temperature stable material on a rotatable frictionwelding tool, rotatably driving said tool and said annular bead at aspeed sufficient to frictionally weld said plurality of workpieces tosaid supporting workpiece, linearly advancing said friction welder tooltoward said workpiece, engaging said annular bead with said workpieces,continue rotating said bead so that said bead makes simultaneous annularcontact with said supporting workpieces and the front faces of saidplurality of said workpieces, forming an annular groove in saidworkpieces by holding said rotating annular bead in fixed alignment withsaid workpieces, frictionally heating and plasticizing material of saidworkpieces in a weld zone defined by said groove, displacing and mixinga portion of said plasticized material of said supporting workpiece intothe plasticized material of said additional workpieces and displacingand mixing a portion of said plasticized material of said additionalworkpieces into the plasticized material of said supporting workpiece,and allowing said plasticized material to solidify and cool to therebysimultaneously weld said workpieces together.